关中地区近期垂直形变与现今活动特征
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摘要
应用差分、回归分析、最小二乘法原理等方法,对泾阳地震前后关中地区跨断层形变资料进行了分析研究,结果显示:①所监测的各断裂活动震前存在着中短期形变异常,呈现出明显的阶段性活动特征,可能是区域大面积应力积累和调整的结果;②进入短期的异常标志是中短期异常出现转折或反向;③各断层活动速率呈准同步变化,曲线形态大都呈现典型的α、β、γ相变化。分析了陕西关中盆地的地壳形变特征以及与西部强震的关系,结果表明:①地壳形变特征存在时空差异性,不同地区地形变活动强弱与其主要边界断裂带的距离存在相关性,主要边界断裂带附近地区相对活动强烈,远处则减弱;②不同时期各断层地形变活动强弱变化不同,既和构造应力场的变化有关,又与地震活动关系密切,且不同区域地壳构造运动发生转折的时期不尽相同。同时,断层形变前兆异常又存在时空差异性,表现为形态、时间等特征的不同;③多场地、大范围的断层活动异常与强震活动相呼应。
By use of generalized regression,least square and differential method,the cross fault deformation data in Guanzhong region before and after Jinyang earthquake had been analyzed.The results show that (1) before earthquake,the activity of monitored faults shows medium and short term deformation anomalies,and the anomalies have the episodic characteristics. (2) the anomalous mark coming into short term is the medium term anomalies to be turned and reversed .(3) the activity rates in each fault show the quasi-synchronous changes and the majority of curve shapes appear as the typical α、β、γ phase changes.We have analyzed the crustal deformation features in Shanxi Guanzhong area and relation to western-part strong shock.The results show that the earth crust structure exists space-time-difference,the deformation activity degree of different area is related to the distance apart from fault zone.The features of crustal deformation and its relation to strong seismic activity of in Guanzhong area are analyzed.The crustal deformation are different in time and space.There is correlation between the intensity of crustal deformation and distance from the boundary fault zone,it means that the deformation is strong in the area near the fault,otherwise the deformation is week.The intensity of crustal deformation in various fault and different period is different,which is related to the change of tectonic stress field and to the seismic activity as well.multi-site and large scale faulting anomaly may echo each other with the strong seismic activity.
By use of generalized regression,least square and differential method,the cross fault deformation data in Guanzhong region before and after Jinyang earthquake had been analyzed.The results show that (1) before earthquake,the activity of monitored faults shows medium and short term deformation anomalies,and the anomalies have the episodic characteristics. (2) the anomalous mark coming into short term is the medium term anomalies to be turned and reversed .(3) the activity rates in each fault show the quasi-synchronous changes and the majority of curve shapes appear as the typical α、β、γ phase changes.We have analyzed the crustal deformation features in Shanxi Guanzhong area and relation to western-part strong shock.The results show that the earth crust structure exists space-time-difference,the deformation activity degree of different area is related to the distance apart from fault zone.The features of crustal deformation and its relation to strong seismic activity of in Guanzhong area are analyzed.The crustal deformation are different in time and space.There is correlation between the intensity of crustal deformation and distance from the boundary fault zone,it means that the deformation is strong in the area near the fault,otherwise the deformation is week.The intensity of crustal deformation in various fault and different period is different,which is related to the change of tectonic stress field and to the seismic activity as well.multi-site and large scale faulting anomaly may echo each other with the strong seismic activity.
引文
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邢西淳,邵辉成,李炳乾,毛娟.2003.陕甘宁青地区的地形变特征与强震活动[J].大地测量与地球动力学,23(4):80～85
张四新,张希.1997.关中地区近期地壳垂直形变特征[J].地震,17(4):404～410
GongShouwen.1998.EvoluionalcharacteristicsofcrustalverticaldeformationinconjonningzonesofmassesandmassivemovementinShaanGanNingQingArea[J].ActaGeophysicaSinica,38(3):329～338(inChinese)
ShaoHuicheng,SuGang,ZhangChunshengandDuChanger.2001.CharacteristicofsmallearthquakeandanalysisonseimicitytrendinGuanzhongregion[J].Inlandearthquake,15(3):218～223(inChinese)
冯浩.1999.有关1997年11月8日西藏玛尼地震震级的讨论[J].国际地震动态,7,20～22
范燕,车兆宏.2003.昆仑山口西8.1级地震前青藏块体边界断层异常活动[J].地震,23(2):121～125
邢西淳,王争良,毛娟,邵辉成.1999.泾阳ML5.2地震的地形变特征[J].地壳形变与地震,19(4):75～79
邢西淳,邵辉成,李炳乾,毛娟.2003.陕甘宁青地区的地形变特征与强震活动[J].大地测量与地球动力学,23(4):80～85
张四新,张希.1997.关中地区近期地壳垂直形变特征[J].地震,17(4):404～410
GongShouwen.1998.EvoluionalcharacteristicsofcrustalverticaldeformationinconjonningzonesofmassesandmassivemovementinShaanGanNingQingArea[J].ActaGeophysicaSinica,38(3):329～338(inChinese)
ShaoHuicheng,SuGang,ZhangChunshengandDuChanger.2001.CharacteristicofsmallearthquakeandanalysisonseimicitytrendinGuanzhongregion[J].Inlandearthquake,15(3):218～223(inChinese)
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